Earlier this month, the Valle Group completed construction on the nation’s 24th certified Passive House, located in East Falmouth, Mass. The house was built virtually airtight and is heated through passive solar gain, according to standards set by the Passive House Institute in Urbana, Ill.

One of these homes was built for empty nesters who wished to downsize. The other is currently a vacation home, but will be a primary residence when the owners retire. The homes have more in common than you’d think.